Managing sediment in Te Awarua-o-Porirua Whaitua PART 1 Presentation to Te Awarua-o-Porirua Whaitua Committee 27.10.2018 Paula Hammond – Policy Advisor
Recap of sediment objectives Sedimentation rate objectives • The net average sedimentation rate is less than 2mm per year in the Pauatahanui Arm (assessed as the rolling average over the most recent five years of data). • The net average sedimentation rate is less than 1mm per in the Onepoto Arm (assessed as the rolling average over the most recent five years of data).
Recap of sediment objectives Muddiness objectives • Sediment mud content does not exceed 20% in the intertidal sediments and should not increase from current state. • Spatial extent of soft mud shall not exceed 15% of the available intertidal area and no increase in soft mud area from current state.
Sources of sediment • Earthworks • Forestry • Erosion prone land – tomorrow’s workshop • Stream bank erosion – tomorrow’s workshop
Earthworks Current policy direction • Permitted activity rules in PCC, WCC and GWRC plans • Policies in PNRP aimed at managing sediment and erosion • PCC - bylaw to prevent silt and sediment entering stormwater • WCC – guide for WSUD stormwater management that includes Earthworks design and construction • GWRC – small earthworks guidelines, erosion and sediment control guidelines
Earthworks recommendations (s4 Pg 27) 1. Wellington City Council considers developing a Silt and Sediment control bylaw similar to PCC’s 2. Greater Wellington reviews publications, including Small earthworks – Erosion and sediment control for small sites, to ensure the methods and principles included are still relevant and applicable. 3. Greater Wellington, in conjunction with WCC and PCC, develop an education and compliance programme to ensure good practice in relation to silt and sediment control is undertaken on small sites. 4. Greater Wellington considers whether to cap the amount of earthworks (areas greater than 3000m 2 ) that are ‘open’ at any one time within the Whaitua.
Forestry Current policy direction • National Environmental Standards for Plantation Forestry – Permits all forestry operations within whaitua, but – Earthworks management plan required for works over 500m 2 – Harvest plans must be prepared for all sites – GWRC can request Earthworks and Harvest Plans and can charge for monitoring permitted activities
Erosion susceptibility classification Level of risk Low – Green Moderate – Yellow High – Orange Very high - Red
Forestry recommendations (s4 Pg 29) 1. Greater Wellington works with the forestry sector to identify barriers to good practice in reducing sediment from forestry operations and discuss what would be most helpful to them to overcome these. 2. Upon receiving notice under the NPS-PF of earthworks, forestry quarrying or harvesting in the Te Awarua-o-Porirua Whaitua, Greater Wellington requests a copy of the Forestry earthworks management plan and harvest plan or Quarry erosion and sediment management plan and actively monitors compliance to ensure sediment discharges to waterbodies are minimised.
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